Since the mid 1980's, efforts have been made to improve the properties, for example, wear resistance and hence the performance of tool coatings. At that time, the common practice was to coat cutting tools with TiN. However, due to its relatively poor oxidation resistance at elevated temperatures, the focus has shifted towards more complex ternary and quaternary compounds, e.g. Ti—Al—N, Ti—Al—Si—N and Ti—Cr—Al—N with improved high temperature performance. For example, Ti—Al—Si—N has been reported as super hard, H >40 GPa, explained in terms of a two phase structure consisting of crystalline phase of NaCl-type in combination with x-ray amorphous Si3N4 or SiNx.
JP 20060082209 discloses a coated cutting tool with a coating comprising an upper layer and an lower layer each formed of (Cr,Al,Zr)N. The upper layer has an average thickness of 0.5-1.5 μm and the lower has an average thickness of 2-6 μm. The upper layer has a laminated structure of a thin layer A and a thin layer B, each thin layer having a thickness of 5-20 nm. The lower layer has the formula (Cr1-x-yAlxZry)N, where 0.55≤x≤0.75 and 0.05≤y≤0.15.
The thin layer A has the formula (Cr1-x-yAlxZry)N, where 0.25≤x≤0.40 and 0.20≤y≤0.30.
The thin layer B has the formula (Cr1-x-yAlxZry)N, where 0.55≤x≤0.75 and 0.05≤y≤0.15.
JP 2006289537 discloses a coated cutting tool with a coating comprising an upper layer and an lower layer each formed of (Cr,Al,Zr)N. The upper layer has an average thickness of 0.5-1.5 μm and the lower has an average thickness of 2-6 μm. The upper layer has a laminated structure of a thin layer A and a thin layer B. Each A and B layer having an average thickness of 5-20 nm. The lower layer has the formula (Cr1-x-yAlxZry)N, where 0.55≤x≤0.75 and 0.05≤y≤0.15.
The thin layer A has the formula (Cr1-x-yAlxZry)N, where 0.01≤x≤0.06 and 0.35≤y≤0.55.
The thin layer B has the formula (Cr1-x-yAlxZry)N, where 0.25≤x≤0.40 and 0.20≤y≤0.30.
WO200605217 discloses a coated cutting tool with a wear resistant coating comprising the following composition Al 1-a-b-c-d CraXbSicBdZ, where X is at least one element from Nb, Mo, W or Ta; Z is one element or compound from N, C, CN, NO, CO, CNO; and 0.2<=a<=0.5; 0.01<=b<=0.2; 0<=c<=0.1; 0<=d<=0.1.
JP2007007765 discloses a coated cutting tool with a coating comprising an upper layer and an lower layer each formed of (Cr,Al,Zr)N. The upper layer has an average thickness of 0.5-1.5 μm and the lower has an average thickness of 2-6 μm. The upper layer has a laminated structure of a thin layer A and a thin layer B. Each A and B layer having an average thickness of 5-20 nm. The lower layer has the formula (Cr1-x-yAlxZry)N, where 0.50≤x≤0.65 and 0.01≤y≤0.10.
The thin layer A has the formula (Cr1-x-yAlxZry)N, where 0.15≤x≤0.30 and 0.35≤y≤0.50.
The thin layer B has the formula (Cr1-x-yAlxZry)N, where 0.50≤x≤0.65 and 0.01≤y≤0.10.
Today industry continuously seeks solutions for economic and high productivity/feed-through manufacturing. To meet these demands there is a need for new materials with advanced properties to improve tool life during operation. Within the metal cutting tool industry, a major part of this effort is focused to improve the wear behavior of the cutting tools by designing the properties of the coating material used in the application. Typically, a high productivity/feed-through cutting process results in a dramatic increase of the tool temperature and hence a coating material with a high temperature wear resistance is essential.